Alkali metal azide complexes of organo-aluminum compounds and uses thereof



Oct. 15, 1968 w. R. KROLL 3,406,187

ALKALI METAL AZIDE COMPLEXES OF ORGANO'ALUMINUM COMPOUNDS AND USES THEREOF Filed Sept. 30, 1964 AI (C2 H5)3 LOW BOILING OLEFINS c OLEFINS DISPLACEMENT 4 /STR'PPER PRODUCT 6 COMPLEXING REACTOR l6 PHASE SEPARATOR C +OLEFlNS m /A|(c H5)32S iii-lg I4 32 DILUENT 31-1-3 1 4 51 DILUENT HEXANE 28 )WASH SODIUM 22 COMPLEX AZIDE fi. gift? VESSEL 42 /3 4 oacom osmow MAKEUP \/EssE| SODIUM AZIDE COMPLEX D INVENTOR.

WQLF R. KROLL A TTORNE Y United States Patent 3,406,187 ALKALI METAL AZIDE COMPLEXES OF OR- GANO-ALUMINUM COMPOUNDS AND USES THEREOF 1 Wolf Rainer Kroll, 715 Clark St., Linden, NJ. 07036 Continuation-impart of applications Ser. No. 92,254, Feb. 28, 1961, and Ser. No. 95,473 and Ser. No. 95,474, Mar. 14, 1961. This application Sept. 30, 1964, Ser. No. 411,171 Claims priority, application Germany, Mar. 15, 1960, Z- 7,877, Z 7,878 42 Claims. (Cl. 260-349) I ABSTRACT OF DISCLOSURE There is disclosed novel processes for preparing alphaolefins containing at least 3 carbon atoms from a low molecular weight mono-olefin reacted with an aluminum compound (AlR AlR OR'+AlR or AlR SR+AlR to provide a growth product, the growth product is converted into a displacement product by treatment with a metal reducing catalyst and further mono-olefin; and thereafter the displacement product is contacted with an alkali metal azide complexing agent which reacts therewith to complex substantially all of the AlR in the displacement product and provide the desired alpha-olefins.

As can be appreciated, the aforesaid process can be adapted for the separation of trialkyl aluminum from other organic compounds and for the separation of alphaolefins from its mixtures with other organic compounds.

Further, the complexes of alkali metal azides with aluminum trihydrocarbons (nAlR -MeN Me is an alkali metal and n is a number having a value of from about 1 to about 2.1) constitute novel materials which can be used (supra) for the separation of aluminum trialkyls from mixtures thereof with other materials, etc.

This application is a consolidation of applications Ser. Nos. 92,254, filed Feb. 28, 1961, 95,473, filed Mar. 14, 1961, and 95,474, filed Mar. 14, 1961, all of which are now abandoned.

This invention relates to a method for the separation of aluminum alkyls from their mixtures with organic compounds. In one aspect, it relates to a process for the recovery of alpha-olefins from their mixtures with trialkyl-aluminums. In another aspect, it relates to novel compositions employed in the separation process.

Heretofore, several methods have been proposed for the production of higher olefins from lower olefins. In general, these proposedmethods have involved the reaction of a trialkyl-aluminum compound with a lower olefin, specifically, ethylene to form the so-called growth product. After forming the growth product, it is heated in the presence of an additional quantity of ethylene and a finely divided metal catalyst, such as finely divided nickel, whereby the higher alkyls linked to aluminum are split off as higher alpha-olefins thereby forming aluminum triethyl or tripropyl, i.e., the so-called displacement reaction. Finally, the higher olefin is recovered from the reaction mass by distillation. The growth reaction may be illustrated equation-wise as follows:

wherein x, y, and z represent integers ranging from 0-14 (average 3-7) and x+y+z=n.

The foregoing reaction may be carried out by passing 3,406,187 Patented Oct. 15, 1968 ethylene through triethyl-aluminum, preferably in the presence of a diluent under a wide variety of reaction conditions, e.g., 65 -l50 C. and ZOO-5,000 p.s.i.g., preferably -l20 C. and LOGO-3,500 p.s.i.g. It is to be understood that, instead of employing triethyl-aluminum as the starting trialkyl-aluminumin the above reaction, other low molecular weight alkyl (C -C aluminum compounds, such as triprOpyLaIuminum, tributyl-aluminum, triisobutyl-aluminum, diethybaluminum hydride, ethylaluminum dihydri de, etc., may be employed; and in lieu of ethylene, other low molecular weight aliphatic mono-1- olefins, such as propylene and the like may be substituted. Generally, C -C olefins are preferred as the growth hydrocarbon compound. g

The higher olefins are produced: by heating growth product, usually at a temperature from aboutSO to about C. for 1 to 30 minutes in the presence of an additional quantity of ethylene and a catalyst, this process being known as the displacement reaction. The displacement reaction can be illustrated equationwise as follows:

wherein RZH, C2H5, C4Hp, C6H13, Etc- It has been suggested that the alpha-olefins and the triethyl-aluminum produced in the displacement reaction can be recovered by fractional distillation. It has been suggested further that, after the separation of the triethylaluminum and the alpha-olefins, the triethyl-aluminum can be returned to the growth reaction and the alpha-olefins to storage. The actual process, however, is not as simple as Equation 2 indicates. This is true, because the triethylaluminum and the alpha-olefins contained in the displacement products tend to undergo a reverse displacement reaction; and for that reason Equation 2 is written as a reversible reaction. Furthermore, under the conditions present, there is a tendency for the alpha-olefins to isomerize at atmospheric pressure. Investigations have demon-' Ethylene Butene-l Hexene-l Octene-l Decene-l Dodecene-l Aluminum-triethyl Tetradecene-l Hexadecene-l Octadecene-l Eicosene-l Higher olefins; unreacted AlR As a specific example, it is impractical to separate triethyl-alurninu'm from dodecene-1 by ordinary methods of fractional distillation because the boiling points of the aluminum triethyl-and dodecene are very close.

It is, therefore, a principal object of the present invention to provide a process for the separation of trialkylaluminum from other organic compounds.

It is anothenobjectof this. invention toprovide a process whereby alpha-olefins containing at least 3 carbon atoms can be producedfrom ethylene by a process which is economical and simple to operate,

Still another object of this invention is to provide a process whereby the alpha-olefins can be readily separated from the other components. v I

.Yet another object of this invention is to provide novel compositions of matter for use in the separation of alphaolefins from other products of the,displacement reaction. Yet another object of this invention is to provide novel aluminum-organic complex compounds.v I I Other objects and advantages of the invention will be apparent as the description proceeds.

,To the accomplishment of the foregoing and related ends, this'invention comprises the features hereinafter fully described andparticul'arly pointedout in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

The foregoing objects are realized broadly by adding to an admixture of trialkyl-aluminum and other organic compound, an alkali metal azide to form a complex of said azide with said trialkyl-aluminum, and separating said complex from said organic compound- In one aspect of the invention the product of a displacement reaction comprising trialkyl-aluminum and alpha-olefins is reacted with an alkali metal azide to form a complex of said azide with trialkyl-aluminum and said complex is separated from the alpha-olefins.

In another aspect of the invention, the complex which is formed between the complexing agent and trialkyl alumimun compound is heatedto release the trialkylaluminum oompound, said compound being reused in the growth reaction and the complexing agent being re.- cycled for reuse in the treatment of the displacement product. i

In still another aspect, the invention comprises as new compositions of matter complexes of alkali metal azides with aluminum trihydrocarbons.

The novel azide aluminum hydrocarbon complexes have the general formula nAlRg-lMeN in which R is any alkyl, aryl, alkylaryl, or aralkyl radical, rt is a num: ber substantially between about 1 and'about' 2.1 and in which Me is an alkali metal. R as alkyl may have any' desired chain length.

The'novel complex compounds and particularly those liquids at room temperature exhibit relatively high thermal stability and may be even handled at elevated temperatures. At high temperatures, especially under vacuum, they can be split into their components. If several cornplex compounds exist between an alkali metal azide and, for instance, an aluminum alkyl, this cleavage takes place stepwise in such manner that the higher complex compounds, as for example the 1:2 sodium azide-aluminum triethyl compound, may he first split into the lower, i.e., the 111.76 compound which may be, in turn, split into the pure components.

The azide complexes are difficulty soluble in nonaromatic hydrocarbons and, if substantially liquid, are immiscible with hydrocarbons. For example, they do not 4 .azide complex into,.for instance,,sodium azideand alumi:

num trialkyl.

If the aluminum hydrocarbon is liquid at the complexing temperature, a solvent is ordinarily not required for the complexing reaction-A solvent may be used, however, if desired, as for instance, for diluent purposes. If the aluminum hydrocarbon is, however, substantially solid at the desired complexing temperatpre which is true, for instance, for-componentswith relatively long alkyl chains, the use of a solvent foreither the azide or the aluminum hydrocarbon, orgfo'r both, may'be necessary. Aromatici oraliphatic hydrocarbons are; usable for this purpose. In that case, if thesolventhasa dissociating action uponthe complex to be formed,-..the conditions, such as concentrations and/or temperature, should be so selected and maintained that dissociation is suppressed or kept at aminimum.

In accordance with one embodiment of the invention, the lower'olefins up to and including C areseparated under vacuum before theformationof the complex-.by passing the displacement product throughafilm evapora- Inanotherembodiment, the lower olefins up to and including C are separated in a film evaporator followed by separation of adodecene aluminum triethyl fraction and then of the, aluminum-free higher'olefins. In this embodiment, only the dodecene-aluminum triethylrfraction is treated with alkali metal azides.

Suitable catalysts for use in the displacement reaction include the so -called reduction catalysts, such asnickel, cobalt, palladium, and certain iron compounds. The preferred catalyst is nickel or a nickel compound; which will react with the trialkyl-aluminum compound. As sec- 0nd choice, the catalyst is cobalt. Specific nickel catalysts dissolve in aliphatic hydrocarbons, cyclohexane or' in liquid olefins. Due to this poor solubility or immiscibility, the novel complex compounds can be used for the separation of aluminum trialkyls from mixtures thereof with other materials. a 1

The higher azide complexes dissociate in suitable solvents into the lower azide complex and free aluminum hydrocarbon, such as aluminum trialkyl. Thus, solvent dissociation into, for instance, aluminum trialkyl and sodium azide occurs when the ratio is below that of sodium to aluminum of the lower azide complex. This dissociation can be used to decompose, by extraction, a higher azide complex into a lower one or even to decompose the lower include finely divided metallic nickel, Raney nickel, nickel acetylacetonate, nickel naphthenate, etc. Karl Ziegler has designated such catalysts in his work on this subject, broadly, as colloidal nickel catalysts. ,The amount of catalyst used can be varied greatly; however, usually the catalyst is employed in amounts from about 0.001 to 0.1 percent based upon the weight of the growth product present. l

. The azides suitable for use as complexing agents are the alkali metal azides, especially sodium. and potassium azides. Lithium azide is, of course, suitable. The alkali azides form complex compounds with aluminum alkyls, -aryls, -aralkyls and -alkylaryls. Preferred are, however, aluminum alkylsandparticularly those which 'aresubstantially liquid at ordinary temperatures (usually up to a;bout an average Q Particularly, advantageous complexing is obtained with aluminum alkyls having lower alkyl chains yieldingsubstantially liquid complex azides as they permit liquid phase operation. Illustrative examples are the alkali and preferably sodium and po-' tassium azides formed with aluminum trimethyl, aluminum triethyl, aluminum .tripr0pyl,-and aluminum triisobutyl.

It has been found that the azide reacts with thetriethyl-aluminum substantially according to the following equations: 1 I

The amount of the alkali metal azide used in the process should be sufiicient to react with all of the triethyl-alumi num present as in Equation 3 or when the alkali metal azide-triethylaluminum complex is used the amount of complex to be added is determinedfrom' Equation 4. Generally, it is preferred to use the theoretical amount as shown by the' equations.

Formation of the alkali metal azide-trialkyl-alumi-Z nurn complexes is usually effected at temperatures ranging from room temperature to about C. In general,

any temperature can be used, since the complexes are for-med equally well at room temperature, as well as at more elevated temperatures. -It is necessary, of course, that the temperature be maintained below the decomposition temperature of the complex. The time required to effect formation of the complex can vary widely but is usuallyfrom 1 to about 30 minutes. The complex compounds (azide-triethyl-aluminum complexes) and the alpha-olefins form separate layers, making it easy to remove the alpha-olefins by decanting, distillation or other similar means. If desired, the recovered alpha-olefins can be washed to remove any residual triethyl-aluminum that may be present in the recovered upper layer. Finally, the alpha-olefins can be subjected to fractional distillation. The complex salt can then be heated, bringing about its decomposition either to the 1.8:1 complex or to the alkali metal azide and the triethyl-aluminum. The thermal decomposition reactions can be illustrated as follows:

It has been found that there is a direct relationship between the temperature at which the complex is heated to bring about its decomposition and the pressure. Speci fically, if the pressure varies from 0.5 to 500 mm. of mercury, a suitable temperature range varies from about 100 to 280 C. Generally, it is preferred to operate under a pressure varying from 5 to mm. of mercury and a temperature varying from 130 to 180 C. As a rule, the temperature used is above the boiling point of the triethylaluminum at the particular pressure employed. operating under such conditions makes it possible to remove the triethyl-aluminum as it is released from the complex causing the reaction to go to completion.

From Equation 2, it will be seen that 3 mols of ethylene per mol of growth product is used. This, however, is the. minimum, and as a rule an excess of ethylene is used. Under normal operating conditions, the reaction isgenerally carried out so that the process is maintained under an ethylene pressure of 20 to 100 atmospheres.

In addition to the procedure hereinbefore described, higher olefins can also be prepared from lower olefins through the reaction of an aluminum compound having the formula: 1

1 AIR OR with a lower olefin. This is accomplished by forming a growth product and displacing higher olefins from said growth product in the presence of additional lower olefin and a catalyst system comprising a reducing metal andan 'alkyl-aluminum compound. When utilizing the alkoxy aluminum compound, the growth reaction takes place as follows:

wherein x and y are defined as in reaction (1), R is a hydrocarbon group which can be alkyl, cycloalkyl, aryl, alkaryl, aralkyl, etc.

The higher olefins are produced by heating the growth product, under conditions of temperature and time as previously set forth, which process is known as the displacement reaction. This reaction can be illustrated equationwise as follows:

wherein R equals H, C 11 C H C H etc. As before, alkali metal azide can be employed to complex with the trialkyl-aluminum, thereby aiding in the separation and recovery of the alpha-olefin product. When the alkali metal azide is employed to complex the trialkyl-aluminum, the complex may form a separate lower layer from the olefins and alkoxy aluminum compound, depending on the particular solvent in which the reaction is carried 7 out and also on the composition of the alkoxy compound. Various methods can be employed in recovering the alphaolefins from the reaction product and complex mixture. For example, the olefins can be distilled until the boiling point of the alkoxy compound is reached, after which this compound can also be removed bydistillation following which the cOmpleX can be decomposed, with -recycling and reuse of the decomposed products as hereinbefore set forth. When the complex forms a .separate lower layer, th alkoxy aluminum compound and olefins can be separated from the complex layer by decantation, with the complex being decomposed separately and the alkoxy compound and olefins being separated by distillation. In .another variation of the recovery procedure, the olefins are distilled, followed by decomposition of the complex and finally distillation of the alkoxy compound. Each of the foregoing procedures find application by the appropriate choice of the OR group to provide an alkoxy compound having the desired boiling point.

It is also within the scope of the invention to employ in place of the aluminum alkoxy compounds materials having the formula:

wherein R and R are defined as previously set forth.

A further understanding of the present invention will be obtained from the following examples which are intended to be illustrative but not limitative of the invention and the scope thereof.

Example 1 21 grams (0.323 mol) .of sodium azide (dried) were reacted with 59 grams (0.518 mol) of aluminum triethyl with stirring at room temperature. Most of the sodium azide reacted at room temperature. To provide reaction of additional sodium azide, the mixture was warmed up to for a few hours. After cooling down and settling, the liquid was decanted and analyzed; aluminum: 17.85 percent; sodium 8.64 percent; ratio of sodium to aluminum in the complex 121.76. About 1.7 grams of sodium azide were regained. The complex was treated two times with the same volume of dodecene at room temperatures. After the last extraction, the top dodecene layer contained 1.14 percent aluminum and smaller than .01 percent sodium, representing 6- percent of the total aluminum of the complex and 0.001 percent of the total sodium. The extremely low sodium valueestablishes that a dissociation of the complex compound takes place.

Example 2 15.5 grams (0.238 mol) of sodium azide were reacted with 83.5 grams (0.732 mol) of aluminum triethyl at room temperature. Most of the solid disappeared at room temperature, and two liquid layers could be observed. In order to complete the reaction, the mixture was warmed up to 80 for several hours. The bottom layer was separated and analyzed. It had an aluminum value of 18.8 percent and a sodium value of 7.5 percent. The ratio of sodium to aluminum was 1:2.1. After extensive washing with hexane and removal of solvent, the analysis showed: 17.95 percent aluminum, 8.5 percent sodium, that is, a sodium-aluminum ratio of 1:1.81. This shows that the higher azide complex is decomposed by extraction to the lower azide complex.

Example 3 compositiomwas stopped: 16 grams of distillate were collected and 8 grams of residue. The distillate had practically theftheoretical aluminum value for aluminum triethyl. The residue was washed with xylene and later with hexane. After extensive drying, 4.9 grams of sodium azide were recovered which amounts to 87 percent decomposition of the complex by heating.

I Example 4 73 grams of 1:2 sodium azide aluminum triethyl complex were extracted with hexane in an apparatus which was suited'for the extraction of liquids,'e.g., a'Schacherl extractoryIn doing so, the volume of the lower phase in the extractorwas continuously reduced, and solid sodium azide was precipitated in this bottom phase after some time. Care was taken that the solid'particles of the precipitated sodium azide were not entrained'by the rising extracting agent, 'which was easily achieved by suitably controlling theextraction velocity. The test was terminated when the liquid lower layer had completely dis appeared and only sodium azide was still suspended in the hexane. The liquid flow was adjusted such that the solid deposit was slightly Whirled high in the lower part of the extraction vessel at the end of the extraction, but nevertheless clear solvent ran off at the top. The duration of the procedure was dependent upon the velocity at which the hexane boiled in the boiling flask of the extraction apparatus. In general, a reaction period of between 10 and 24 hours was suflicient. However, this period could be shortened by suitable measures.

After having distilled off the hexane, pure aluminum triethyl in amount of 57 grams was left in the boiling flask of the extractor.

- Example 5 Example 6 27. grams of potassium azide (dry) were reacted with 39 grams of aluminum triethyl. In doing so, heating without gas evolution was observed. ,When heating to 65 C. (still more rapidly when heating up to 120 C.) and vigorously stirring, a clear solution was obtained which, after cooling, got viscous at .room temperature and from which several crystals were only separated when allowed to stand for an extended period of time. The viscous liquid had exactly the composition To this mixture were added further 39 grams of aluminum triethyl, which again resulted in heating up. After heating to about 70 C;, a single clear phase was obtained which got viscous after cooling. This 2:1 complex was found to be insoluble in additional aluminum triethyl and sparingly soluble in n-hexane.

I Example 7 4 grams of sodium azide were stirred with-35 grams of aluminum tri-isobutyl (i.e., more than required for the formation of the 1:2 sodium azide-triisobutylalu minum complex) and heated up to 70 C. In doing so, the

. 8" (1954), 110, 65 grams of thoroughlydried'sodiiiihfazide? were extensively wet-groundfunder a protective gas atmosphere (nitrogen orlargon) with 145 grams of am: minum trimethyl and 200 ml. of dry octane. From time to time, the mixture was allowed to settle and a sample of the supernatant octane was taken todetermine its alu minum content.' The reaction was completed as soon as the aluminum value had dropped to avery loweoristant value. The suspension of the solid complex rormeawas discharged and allowed to settle. 'The supernatant s'ol-' vent was poured oti and the octane was evaporated from the remaining slurry under vacuum at to C. The complex NaN 2Al(CH was obtained as a "white Powder. i l i Example 9 A growth product was prepared'by reacting aluminum triethyl with ethylene at 150 atmospheres and C. 1330 grams of the growth product having an average composition of Al((C H C H were mixed with 0.1 gram of nickel acetyl acetonate and then converted in known-manner'with ethylene into 1470 grams'of'a reaction product which contained 265 grams of aluminum triethyl in addition to olefins. This growth product contain ing the nickel. catalystwas displaced in a continuously operating apparatus with an excess of ethylene (50 atmos pheres) at. 105. C.'.The displacement product (.1470 grams) which contained 265 grams of aluminum tr iet h yl was stirred with 76 grams of ,sodium azide at room tem-. perature under a-slight superatmospheric pressure of ethylene. Two liquid layers were formedfThebottom layer (341 grams) represented the 1:2 sodium .azide-t-ri ethyl complex. Thetop layer was removed by siphoning. It contained only traces of aluminum-organic compound and consisted of alpha-olefins having a purity in excess of98%." 'f I.

. I Example 10 A mixture of 456 grams of aluminum triethyl and 323 grams of tetraethyl lead which, for'ex'ample, might be obtainedby electrolysi'swas stirred with grams of dry sodium azide. Complexingbetween the sodium azide and aluminum triethyl commenced already atroom tem: perature. It was completed if the interface 'of the 'two liquid phases'did no longer shift. The upper liquidphasc then consisted of the 1: 2 sodium azide-triethyl'complex' and the bottom phase consisted of almost pure tetraethyl lead. The two liquid phases could be-separatedconveniently by siphoning. 1

- Example 11 Decomposition of a low azide complex haviiig a ratio of sodium to aluminum as 1:1.82. 24 grams of this com plex were decomposed for 1 hour under a'vacuumof 0.8 mm. Hg and at 100 C. The reaction mixture got sodium azide was completely dissolved. After cooling,

the formation of a second phase was not observed. This means that the 1:2 complex formed is soluble inan excess of aluminum tri-isobutyl.

v v Example 8 I In a ball mill as described in Liebigs Annalen, 589,

viscous and it was impossible to stir at the end. 16 grams distillate and 24 grams residue were collected. The distillate was practically pure aluminum triethyl, which was proved by analysis. The residue was washed with xylene and later with hexane. After extensive drying, 4.9 grams sodium azide were recovered-,rwhich corresponded-to an 87% decomposition. 2 In order to more clearly describe the-invention and provide a better understanding thereof, reference is had to the accompanying drawing which is a diagrammatic illustration of an. extractive distillation system suitable for carrying out the invention.

Referring to the drawing, displacement'product' com prising a mixture of alpha-olefins and aluminum triethyl was introduced to stripper, 4 through conduit 2. Within the stripper, which was heated by reboiler 4, separation was eifected whereby low boiling olefins (C and lower) were removed from the displacement product, being with-' 9, drawn from the stripper through conduit 10, combined With sodium azide through conduit 12 and introduced to a complexing' reactor and phase separator 14. The latter ,vessel was maintained under suitable temperature and pressure whereby the sodium .azide complexed with the triethyl-aluminum. As a result of this reaction, two phases were formed in vessel 14, an upper phase 16 comprising principally C olefins and a lower phase 18 comprising sodium azide-triethyl-aluminum complex and diluent. The upper phase was withdrawn from vessel 14 through conduit'20, and the complex and diluent were withdrawn through conduit 22, combined with wash hexane through conduit 24 and introduced to wash vessel 26. In the wash vessel,-a mixture :of hexane and diluent separated from the complex toform an upper phase 28 which Was withdrawn from the wash vessel through conduit 32. The complex, which accumulated as a separate phase 30 in the bottom of the wash vessel, was removed through conduit34 and introduced to decompositionvessel36 wherein an elevated temperature Was maintained, sufiicient to decompose the complex. In vessel 36 aluminum triethyl was distilled from the complex, leaving a residue of sodium, azide and undecomposed lower azide complex. Heat required for decomposition in vessel 36 was provided bya reboiler (not shown). Aluminum triethyl was withdrawn from vessel 36 through conduit 38, and, as desired, could be recycled for reuse in the growth or displacement reactions. Heated complexing agent was withdrawn from the decomposition vessel through conduit 40. If desired, this material could be returned to the complexing reactor and phase separator through conduit 12.

, During the preceding process, losses of complexing agent from the system can occur, and make-up material was therefore provided through conduit 42 as required.

The following example is presented in illustration of an application of the invention on a commercial scale, as embodied in the aforedescribed drawing:

Example 12 Wt. Pounds percent per hour Flows:

' Displacement product to stripper (2) 100 Composition:

C1 to C30 olefins. 65.1 45 A1(C:H5)3 17. 3 Diluent (isooctane 17.6 Stripper bottoms to reactor (10) 63. 7

Composition:

010 to C30 olefins 72.8 Al(O:H5)3 27.2 Sodium azide to reactor (12)... 5. 5

Complex to wash vessel (22) 21. 9 5O Composition: .NaNa 1.8Al(CgH5) 98. 1

, NaNx 1. 4 01 to C 0 olefins- 0. 5 Hexane to wash vessel (24) I Complex to decomposition vessel (84) Composition:

- NaNa-lfiAKCzHs): 98. 6 N 8N3 1. 4

Temperatures:

Stripper (4): Top 0 Bottom 100 Complexing reactor and phase separator (14)... Wash vessel (26) 25 Decomposition vessel (36) Pressures: Mm. Hg

Stripper (4) 20 6 Complexing reactor and phase separator (14).... 760 Wash vessel (26) 760 Decomposition vessel (36) 0.8

of aluminum alkyls from other metal alkyls suchas lead tetralkyls, and the like.

While particular embodiments of the invention have been described, it will be understood, of course, that the inventionis not limited thereto, since many modifications may be made; and it is, therefore, contemplated to cover by the appendedclaims any such modifications as fall within the true spirit and scope of the invention. As will be apparent to those skilled in the art, the invention is applicableto the production of even-numbered and odd-numbered and straight-chain and branched-chain alpha-olefins. Even numbered alpha-olefins are produced when triethyl-aluminum is reacted with ethylene. after which the resulting growth product is treated in accordance with my invention. Odd-numbered alpha-olefins are produced when tripropyl-aluminum is substituted for triethyl-aluminum in the reaction. Variations in procedure which can be used within the scope of the invention include stripping the mixture of alpha-olefins and trialkylaluminum to remove lower olefins up toiabout C complexing the trialkyl-aluminum with the alkali metal azide, separating the two layers thereafter formed by decantation, heating the bottom layer (complex) to decompose the complex and thereafter recycling thev decomposition products for reuse in the process. In another procedure, stripping and formation of the complex is again carried out as above, with the distinction that the lower metal azide complex is reacted with the trialkyl-aluminum-rather than the metal azide. In this procedure, after the separation by decantation, the higher complex is decomposed to the lower complex which is then recycled to the process. In still another procedure, displacement product is distilled into three fractions, a lower olefin fraction and aluminum trialkyl plus dodecene fraction, and a residue of high boiling olefins. In this method, only the intermediate product is complexed. In still another procedure; the azide complexes instead of being thermally decomposed are extracted with a suitable solvent, for example, an aliphatic or aromatic hydrocarbon by continuous extraction.

It is also within the scope of the invention to prepare 1.8:1 azide complex from the 2.1:1 complex in accord-' ance with the following reaction:

The complex compounds of the alkali metal azides and trialkyl-aluminum provide a number of advantages in the process of this invention. Under the conditions of the process, the complexes are liquid and thus are easily handled. They possess the further advantages that they are formed at room temperature and are easily decomposed, thus allowing reuse of the individual components of the complexes in the preceding process steps. Due to their high conductivities the complexes also have utility for uses where this property is important, for example, in the manufacture of lead alkyls by the electrolytic process.

As pointed out previously, the products of the displacement reaction tend to undergo a reverse displacement re action, and further there is a tendency for the alpha-olfins to isomerize, both of these conditions being accelerated by the catalyst employed in the displacement reac- 5 tion. It has been found that various materials can be employed which exent a poisoning or inhibiting effect on the catalyst, thereby minimizing the reverse displacement reaction and also the tendency of the alpha-olefins to isomerize. For example, it has been found that the alkali metal cyanides, particularly, sodium andpotassium cyanides, are effective poisons for the catalyst. It has also been found possible to poison the catalyst :by the addition of acetylenic compounds, such as phenyl acetylene, as described in German Patent No. 1,034,169 to Karl Ziegler. In addition, acetlyene alcohols such as propargyl alcohol, can be employed as a catalyst poison. It is within the scope of the invention to employ any of these or any other catalyst poisons in the herein-described process, said poison being added to the displacement product prior to addition of the alkali metal azide complexing agent. Generally, only small amounts of the poison'are required to eifectively inhibit the undesired reactions. For example, when employing alkali metal cyanide, an amount from about 5 to 500 parts per part by weight of catalyst is generally used.

The invention having thus been described, what is claimed and desired to be secured by Letters Patent is:

'I claim:

1. In a process for the preparation of alpha-olefins having a carbon content of at least three in which a material selected from the group consisting of AlR3,

and AlR SR'+AlR in which R is a low molecular weight alkyl group, R is a hydrocarbon group and R and R can be alike and unlike, is reacted with a. low molecular weight aliphatic mono-l-olefin to provide a growth product, said growth product is heated in the presence of a metal reducing catalyst and an additional amount of said low molecular weight aliphatic mono-l-olefin to provide a dis-- placement product, the improvement which comprises adding to said displacement product a complexing agent comprising alkali metal azide in an amount sufficient toreact with and form a complex with substantially all of the AIR;, in said displacement product and recovering alpha-olefins from said complex.

2. The process of claim 1 in which the reducing catalyst is nickel, the material reacted with the low molecular weight aliphatic mono-l-olefin is triethyl-aluminum, said l-olefin is ethylene and the complexing agent is selected from the group consisting of alkali metal azide and complex of alkali metal azide and 'AlR 'ir1 which the molecular ratio of said AlR to said alkali metal azide is 18:1.

3. The process of claim 2 in which the alkali metal azide is sodium azide.

4. In a process for the preparation of alpha-olefins having a carbon 'content of at least three in which a material selected from the group consisting of AlR and AlR SR+AlR in which R is a low molecular weight alkyl group, R' is a hydrocarbon group and R and R can be alike and unlike, is reacted with a low molecular weight aliphatic mono-l-olefin to provide a growth product, said growth product is heated in the presence of a metal reducing catalyst and an additional amount of said low molecular weight aliphatic mono-l-olefin to provide a displacement product, the improvement which comprises adding to said displacement product a compound selected from the group consisting of alkali metal azide and complex of alkali metal azide and AlR in which the molecular ratio of said AlR to said alkali metal azide is 1.8: 1, said compound being present in an amount sufficient to react with and form a complex with substantially all of the AlR present in said displacement product, allowing the resulting reaction product to separate into two layers, an upper layer comprising materials selected from the group consisting of alpha-olefins, AlR OR+alpha-olefins, and AlR SR'+alpha-olefins, and the lower layer comprising alkali metal azide-MR complex wherein the molecular ratio of said AlR to said alkali metal azide varies from 1.821 to 21:1, separating the upper layer and recovering the alpha-olefins therefrom.

5. The process of claim 4 in which the reducing catalyst is nickel, the alkali metal azide is sodium azide, the material reacted with the low molecular weight aliphatic mono-l-olefin is triethyl-aluminum and said l-olefin is ethylene.

6. In a process for the preparation of alpha-olefins having a carbon content of at least three in which a trialkylaluminum compound is reacted with a low molecular weight aliphatic mono-l-olefin to provide a growth product, said growth product is heated in the presence of a metal reducing catalyst and an additional amount of said low molecular weight aliphatic mono-l-olefin to provide a displacement product, the improvement which comprises adding to said displacement product a compound selected from the group consisting of alkali metal azide and complex of alkali metal azide and AlR in which the molecular ratio of said AlR to said alkali metal azide is 1.8:1, said compound being present in an amount sufficient to react with substantially all of the AlR allowing the resulting reaction product to separate into two layers, ari upper layer comprising the alpha-olefins and the lower layer comprising alkali metal azide-AlR complex wherein the molecular ratio of said AlR to said alkali metal azide varies from 1.821 to 2.111, separating the upper layer and recovering the alpha-olefins therefrom, heating said lower layer to decompose at least a portion of said alkali metal azide-AlR complex, separating released AlR compound and returning said compound to the growth reaction and recycling undecomposed alkali metal azide-AIR; complex and alkali metal azide for reuse in the process.

7. The process of claim 6 in which the reducing catalyst is nickel,the alkali metal azide is sodium azide, the material reacted with the low molecular weight aliphatic mono-l-olefin is triethyl-aluminum and said l-olefin is ethylene.

8. In a process for the preparation of alpha-olefins having a carbon content of at least three in which a trialkylaluminum compound is reacted with a low molecular weight aliphatic mono-l-olefin to provide a growth product, said growth product is heated in the presenceof a metal reducing catalyst and an additional amount of said low molecular weight aliphatic mono-l-olefin to provide a displacement product, the improvement which comprises adding to said displacement product a compound selected from the group consisting of alkali metal azide and complex of alkali metal azide and AlR in which the molecular ratio of said AlR to said alkali metal azide is 1.821, said compound being present in an amount sulficient to react with and form a complex with substantially all of the AlR present in said displacement product, allowing the resulting reaction product to separate into two layers, an upper layer comprising the alpha-olefins and the lower layer comprising alkali metal azide-A111 complex wherein the molecular ratio'of said AlR to said alkali metal azide varies from 1.821 to 2.1:1, separating the upper layer and recovering the alpha-olefins therefrom, heating said lower layer to decompose said alkali metal azide-AlR complex to release AIR;, and form alkali metal azide and 1.8:1 complex of AlR with alkali metal azide, separating released AlR compound and returning said compound to the growth reaction and recycling alkali metal azide and said 1.8:1 complex for reuse in the process.

9. The process of claim 8 in which the reducing catalyst is nickel, the alkali metal azide is sodium azide, the material reacted with the low molecular weight aliphatic monol-olefin is triethyl-aluminum and said l-olefin is ethylene.

10. A novel aluminum-organic complex compound of aluminum hydrocarbons and alkali azides having the general formula nAlR lMeN wherein n is a number of between 1 and 2.1, R is a hydrocarbon radical and Me is an alkali metal.

11. Novel compound according to claim 10 in which R is an alkyl radical.

12. Novel compound according to claim 10 in which R is a lower alkyl radical.

13. Novel compound having the general formula 2Al(C H -1NaN 14. Novel compound having the general formula 1.76 Al(C H -1NaN 13 15. Novel compound according to claim 10 having the general formula 2Al(C H -1KN 16. A novel compound having the general formula 17. Process for producing novel aluminum-organic complex compounds which comprises reacting an alkali metal azide with an aluminum trihydrocarbon.

18. Process according to claim 17 in which said trihydrocarbon is a trialkyl.

19. Process according to claim 18 in which said reaction is effected in the presence of a solvent for at least one of the reactants.

20. Process according to claim 19, in which said reaction is effected by a temperature of between 50 and 120 C.

21. A novel aluminum organic compound consisting of a complex compound of aluminum trialkyl and alkali metal azide.

22. A method of separating aluminum trialkyls from mixtures thereof with organic compounds selected from the group consisting of olefins, boron alkyls and lead tetraalkyls, which comprises treating said mixtures with an alkali metal azide and separating the resultant complex compound of alkali metal azide and aluminum trialkyl.

23. The method of claim 22, wherein mixtures of aluminum trialkyls and olefins are separated.

24. A method of separating aluminum trialkyls from mixtures thereof with organic compounds selected from the group consisting of olefins, boron alkyls and lead tetraalkyls, which comprises treating a mixture of aluminum trialkyls and olefins derived from the treatment of higher aluminum trialkyls with lower olefins and comprising lower aluminum trialkyls and higher olefins with an alkali metal azide and separating the resultant complex compound of alkali metal azide and aluminum trialkyl.

25. The method of claim 22, wherein the complex com pounds of alkali metal azides and aluminum trialkyls are separated from the rest of the organic compounds' by formation of layers.

26. The method of claim 22, wherein said complex compounds of alkali metal azides and aluminum trialkyls are separated from the rest of the organic compounds by distillation.

27. The method of claim 22, wherein an excess of aluminum trialkyl is present, in which the higher azide complex compounds formed are split into lower azide complex compounds and in which said lower complex compounds are again used with such mixture for the formation of higher complex compounds.

28. The method of claim 27, wherein said splitting is effected by heating at temperatures up to 150 C.

29. The method of claim 27, wherein said splitting is effected by vacuum.

30. The method of claim 27, wherein said splitting is effected by extraction with a non-aromatic hydrocarbon.

31. The method of claim 22, in which the amount of azide present yields the lower azide complexes in which the latter are split into alkali azides and aluminum trialkyls and in which said alkali metal azides are again used for complexing with such mixture.

32. The method of claim 31, wherein said splitting is effected at temperatures up to C.

33. The method of claim 31, wherein said splitting is effected under vacuum.

34. The method of claim 31, wherein said splitting is effected by extraction with a non-aromatic hydrocarbon.

35. The method of claim 24, wherein all of the olefins up to and including C are removed by distillation prior to the complex formation.

36. The method of claim 24, wherein the product to be separated is separated by distillation into a fraction containing lower olefins up to and including C a second fraction containing dodecene-aluminum triethyl, and a third fraction containing higher olefins, and in which only the second fraction is treated with azides.

37. A cyclic process for the production of alpha-olefins according to claim 24, which comprises preparing higher aluminum trialkyls by subjecting lower aluminum trialkyls and ethylene to the growth reaction; displacing from said higher aluminum trialkyls the higher alpha-olefins by means of lower olefins; treating the resultant displacement products with alkali metal azides; separating the complex compounds from the olefins; splitting the complex compounds and reusing the resultant alkali metal azides for complexing and the resultant aluminum triethyl for the growth reaction.

38. The method of claim 37, wherein said displacement is effected in the presence of nickel compounds as the catalysts.

39. The method of claim 37, wherein lower azide complexes in place of said alkali azides are used for the complex formation and the higher complexes are only partially split to the lower alkali metal azide complexes.

40. The method of claim 22, wherein mixtures of aluminum trialkyls with lead tetraalkyls are separated.

41. The method of claim 22 in which mixtures of aluminum trialkyls with boron alkyls are separated.

42. The method of claim 41 in which said aluminum trialkyls and said boron alkyls are normal liquid lower alkyl compounds.

References Cited UNITED STATES PATENTS 2,863,896 12/1958 Johnson 260-448 2,889,385 6/1959 Caterall et al. 260-448 3,098,862 7/ 1963 Kobetz 260-448 TOBIAS E. LEVOW, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,406,208 October 15, 1968 Bruno Blaser et al.

It is certified that error patent and that said L shown below:

appears in the above identified etters Petent are hereby corrected as Column 11, line 70, before "B.P."

insert an opening parenthesis; same line 70, "0.5" should read 0.05 Co1um1 14, line 30, "hralides" should read halides Signed and sealed this 3rd day of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents 

